This invention relates to separating chute system, namely a chute system having two discharge passage routes.
In a conventional combinatorial weighing apparatus, weight values of articles are obtained by plural weighing machines and a total weight or number of a batch or combination of articles that is equal or closest to a preset weight or a preset number within preset allowable limits is computed by combinatorial reckoning based on the aforementioned weight values. In such apparatus, the articles thus selected and discharged from the corresponding weighing machines are collected in the manner described below.
Specifically, as shown in FIG. 1, the weighing machine is made up of a plurality of weighing hoppers and weight sensors associated therewith. The weights of articles supplied into these weighing hoppers (A1), (A2), . . . (An) are measured by associated weight sensors (B1), (B2), . . . (Bn), and total weights of all possible combinations of articles are computed by a computer, with the number of articles of the combinations being arbitrary or predetermined. These total weights are compared with a preset target weight, whereby the weight combination that gives the predetermined weight or the value closest thereto within preset allowable limits is found for each weighing cycle. Then, only those weighing hoppers that are specified by said weight combination are opened, thereby discharging their contents into a common discharge chute C which in turn discharges the articles into a timing hopper D where they are collected.
Alternatively, the weight values found by the weight sensors (B1), (B2), . . . (Bn) are divided by a unit article weight to give the number of articles contained in each weighing hopper and different combinations of article numbers are added by a computer. Thus a combination of article numbers that gives a total article number equal or closest to a preset article number is found for each weighing cycle and the articles in the article number combination thus found are discharged from the weighing hoppers and collected together.
Although higher accuracy may be realized with these combination weighing operations, there is increasing demand for a combinatorial weighing apparatus with an even higher weighing capacity. To improve weighing capacity, it is necessary not only to elevate the rate of supply and the measuring speed but also to collect the articles efficiently each time the articles are discharged after each weighing operation.
To this end, various collecting chute configurations have been devised, as shown by way of examples in FIGS. 2 through 4. The chute system shown in FIG. 2 comprises a collecting chute 3 having an inlet opening 1 and an outlet opening 2 and an intermediate shutter 4 suspended on top of a discharge outlet 2. A predetermined number of weighing hoppers A are arranged on top of the inlet opening 1 of the collecting chute 3. The articles are discharged from the weighing hoppers A on opening the hoppers A and are collected by the collecting chute 3 and supplied to a timing hopper D mounted below the collecting chute 3. The intermediate shutter 4 is raised and lowered depending on the rate of descent of the articles. Thus, articles discharged from the weighing hoppers A are separated from the articles discharged in the subsequent weighing cycle at the mid-portion of the chute 3 and are collected in the timing hopper D.
In this manner, it is possible to carry out the combinatorial weighing operation with the articles discharged from the weighing hoppers A at double the ordinary rate, because the articles discharged by the previous cycle are separated by the intermediate shutter 4 from the currently discharged articles and thus may be collected in the timing hopper D.
However, when the collecting chute 3 is constructed in this manner, it is necessary to provide a mechanism for vertically displacing the shutter in synchronism with opening and closing of the weighing hoppers A, thus complicating the construction of the apparatus. Moreover, the discharge capacity cannot be increased beyond a certain limit because of the provision of a movable device within the collecting chute 3.
In addition, since the collecting chute 3 has only one discharge opening 2, it is necessary to provide a distributing device when the combinatorial weighing apparatus is operatively linked to a twin tube packaging device. In such case, the operating capacity of the distributing device is critical for optimum performance of the packaging machine. In addition, great difficulty may be experienced when both tubes of the twin tube packaging machine, operatively linked with the combinatorial weighing apparatus, are operated simultaneously.
FIGS. 3 and 4 show an example of the conventional separate type collecting chute having a discharge passage divided into two routes. An inner chute section 5 and an outer chute section 6 of inverted frusto-conical shape are arranged to intersect each other so that upper supply openings 7 and 8 thereof are arranged concentrically with respect to each other and the lower discharge openings 9 and 10 are arranged in a side-by-side relation. The narrow discharge passage defined between the outer chute 6 and the inner chute 5 is cut out partially for providing an independent dual discharge passage.
In operation, weighed articles are injected into the outer chute 6 and the inner chute 5 from a predetermined number of the weighing hoppers B each having a dual discharge passage and being mounted around the upper rim of the supply openings 7, 8 of the inner and outer chutes. The weighed articles are collected separately by these chutes which in turn discharge them separately into discharge hoppers.
With this system, the configuration of the chutes 5 and 6 is necessarily complicated. Moreover, it is not possible to discharge the articles from all of the weighing hoppers B into either of the inner and outer chutes 5 and 6, resulting in a limitation upon the combinatorial computations. In addition, great difficulty may be experienced in terms of accuracy and function when the combinatorial weighing apparatus is to be operatively linked with a single tube high-speed packaging machine or a twin tube alternating-type packaging machine.
It may be contemplated to have the overall periphery of the inner chute 5 covered by the outer chute 6 so that weighed articles may be discharged from the outer chute 6 into any of the inner or outer chutes 5 and 6. However, in this case, a difference may arise in the discharge capacity of the inner and outer chutes 5, 6 because the angle of the inclined surface of the inner chute 5 is markedly different from that of the outer chute 6, which in turn gives rise to a differnce in the angle of different portions of the same chute. In addition, a narrow discharge passage is defined in the intersecting portion between the outer chute 6 and the inner chute 5, resulting in a considerable difference in the discharge capacity of the inner and outer chutes 5, 6, and a difference in the weighing hopper discharge position even with one and the same chute.